A virtualization technology is a decoupling technology in which a bottom-layer hardware device is separated from an upper-layer operating system and application program. As one of important bottom-layer technologies for supporting a currently popular cloud computing platform, the virtualization technology may greatly improve resource utilization of a physical device. Compared with a conventional physical server, a virtual machine (VM) has better performance in the terms of isolation and encapsulation, and may save information of the whole VM in a virtual disk image (VDI), which may facilitate operations such as a snapshot, a backup, a clone, and distribution for the VM. An overhead is generated by virtualization, thereby causing that with a same configuration, performance of a VM is poorer than performance of a physical machine. How to effectively improve performance of a VM is a problem that needs to be solved in this field.